I just recently bought a Sport 2 556 and was wondering could i replace the upper with a 22 lr when i want to do alot of shooting or would i be better off just buying a whole new one for that

Yes, if you purchase a dedicated .22lr upper, you can just switch it out. To be clear, it has to be a true AR upper with a .22lr barrel and bolt assembly... The M&P 15-22 will not fit on a 5.56 lower.

Your other option is to just use the .22lr bolt conversion kit, but these are not as accurate as a dedicated upper. But they are cheaper.

I have a CMMG .22lr upper, on a CMMG lower with a Redi Mag adapter installed that allows me to use M&P 15-22 magazines. Bolt locks open when empty, so functions just like the 5.56.

Thanks for the reply and suggestions where i should buy the upper from

Does anybody know the trigger pull weight on it?

Know what’s better than I rifle? 2 rifles. Seriously, you’ll spend near as much on a 22 upper so might as well get a dedicated 15-22. Functions just like an AR. Trigger is milspec but you can get aftermarket if you want.

I spent more on my CMMG Quebec A (complete rifle, .22lr upper on standard lower) than I spent on my son's M&P 15-22.

There are pros and cons to the complete upper vs. the 15-22.

Pros for the upper are that you get a rifle that has the same weight and feel, since it is made from forged aluminum.

With the upper, you also get to practice with the same trigger as your 5.56... not the same model, but the same trigger.

Cons against the .22lr would be cost and that I had to add extra parts to my rifle to get it to hold the bolt open after the last shot. M&P 15-22 had that function right out of the box. The adapter I added also allowed me to use M&P 15-22 magazines, which are cheaper and more readily available at local big box stores.

Thanks to all for the replies, i was doing some searching and found buying a the upper is more expensive then just buying the base model from Smith and Wesson so i will probably be doing that as it's cheaper and again thanks for the info

It has been 5 mos since this posted and MP15-22 prices have dropped:

Kit- $320/$304 (non-member)
Smith & Wesson M&P15-22 Sport Kit, Semi-Automatic, .22LR, with Red Dot and Soft Case, 25+1 - 708227, Semi-Automatic at Sportsman's Guide

Rifle only- $299/$284 (non-&member)
Smith & Wesson M&P15-22 Sport, Semi-Automatic, .22LR, 25+1 Rounds - 710492, Semi-Automatic at Sportsman's Guide

Definitely better to just buy one.